1. Field of the Invention
The instant invention relates to a method for converting phosphorus polymers from a two dimensional, layered structure into a three dimensional structure by crosslinking such layers with inorganic moieties. Preferably, the method and the resulting crosslinked polymers are used to encapsulate active materials such as catalysts, pesticides, etc. by intercalating such active materials between the layers prior to crosslinking. The active materials may also be the crosslinking agents or precursors. The egress of said active materials into the environment during use may be hindered or prevented by the crosslinked structure of products of this invention. Ingress of material from the exterior to the interior of the crosslinked polymers will be restricted by the crosslinks as well.
2. Background of the Prior Art
Methods for encapsulating an active moiety are well known in the prior art. Such methods may comprise surrounding an active moiety, such as a drug, pesticide, etc., by a polymeric material. The encapsulated product can be designed to allow the active moiety to permeate through the capsule wall into the environment of use over a period of time (slow release) or the capsule can be utilized by abrupt rupture to release the active moiety into an environment immediately. The capsule can also be used by allowing a reactant to permeate through the wall for interaction with the active moiety within the capsule and the reaction products recovered by back permeation or immobilized inside the capsule. In general, the above described encapsulated products utilize a polymeric material functioning as a membrane to isolate the active moiety from environment or control the passage of the active moiety into the environment.
It is also known that various separations can be effected with materials having pores which are designed to admit the passage therethrough of molecules of less than a certain size while prohibiting the passage of larger molecules. For example, the crystalline aluminosilicates known as zeolites have been utilized for the separation of molecules on the basis of molecular size.
A novel class of compounds has now become known, which compounds may be described as inorganic polymers. These compounds are described in U.S. Pat. Nos. 4,232,146; 4,235,990; 4,235,991; 4,256,872; 4,267,308; 4,276,409; 4,276,410; 4,276,411; 4,298,723; 4,299,943; 4,373,079; 4,384,981; 4,386,013; 4,390,690; 4,429,111; and 4,436,899 which are hereby incorporated by reference. These compounds may be prepared having a layered structure similar to the layered structure of zirconium phosphate. The above patents teach that these novel layered compounds have many uses. However, although these layered compounds may be formed with a "pillared" structure by synthesis from bifunctional acids comprising a Group V atom, it has nowhere been disclosed that such compounds may be converted from their normal two-dimensional (layered) structure into a three-dimensional structure, after synthesis, by crosslinking said layers.
U.S. Ser. No. 614,111, by Callahan et al., filed May 24, 1984, discloses crosslinking the above novel layered compounds and Zr(O.sub.3 POH).sub.2, generally with bisphosphonic acids. It has also been disclosed that monophosphonic acids may be exchanged into the above layered compounds after synthesis. However, the purpose of such exchange was to vary the pendant functional groups within the layers, not to crosslink the layers and provide a three-dimensional structure.
Finally, U.S. Pat. No. 4,386,013 teach that the method of U.S. Ser. 614,111 may be utilized to prepare catalysts, such as hydrogenation and hydroformylation catalysts which are resistant to leaching. Such teaching is hereby incorporated by reference to show one embodiment of the instant invention.